N-[2-Substituted-1-oxoalkyl]-2,3-dihydro-1H-indole-2-carboxylic acid derivatives

ABSTRACT

Disclosed herein are 2,3-dihydro-1H-indole-2-carboxylic acids substitued on the nitrogen with 3-mercapto-2-alkyl-1-oxoalkyl, 3-phosphoryl-2-alkyl-1-oxopropyl, or 2-amino-2-alkyl-1-oxoalkyl derivatives which act as inhibitors of angiotensin converting enzyme and as antihypertensive agents. The compounds of the invention (excluding disclosed intermediates) have the general formula: ##STR1## wherein: n is 1 or 0; 
     R 1  is hydrogen, lower alkyl, aryl or aralkyl; 
     R 2  is hydrogen or lower alkyl; 
     R 3  is hydrogen, lower alkyl or aroyl; 
     R 5  is hydroxy, amino, or lower alkoxy; 
     X is hydrogen, hydroxy, lower alkyl, lower alkoxy, or halogen; Y is hydrogen, lower alkyl, or aryl; 
     Y is hydrogen, lower alkyl, or aryl; 
     R 4  is ##STR2##  wherein: L is O, NR 7  or S (where R 7  is hydrogen or lower alkyl); 
     M is R 8 , OR 8 , SR 8 , or NR 9  R 10  (where R 8  is hydrogen, lower alkyl, aryl, or aralkyl; and R 9  and R 10  are, independently, hydrogen, lower alkyl, or aryl); 
     A is O, NR 13  or S; 
     R 11  and R 12  are, independently, hydrogen, alkyl, aralkylor aryl; 
     R 13  is hydrogen or lower alkyl; 
     m is 0, 1, 2, or 3; 
     R 20  is hydrogen or aryl; and 
     R 21  is hydroxy or lower alkoxy; or pharmaceutically acceptable salts thereof. 
     Claimed compounds are intermediates of the formula: ##STR3## wherein R 15  is hydrogen or lower alkyl.

This application is a divisional of Ser. No. 06/284,433, filed July 20,1981, now U.S. Pat. No. 4,350,633 which is a continuation-in-part ofSer. No. 164,992, filed July 1, 1980, now U.S. Pat. No. 4,303,583 whichis a continuation-in-part of Ser. No. 06/065,817, filed Aug. 13, 1979.

This invention concerns 2,3-dihydro-1H -indole-2-carboxylic acidssubstituted on the nitrogen with 3-mercapto-2-alkyl-1-oxoalkyl,3-phosphoryl-2-alkyl-1-oxopropyl, or 2-amino-2-alkyl-1-oxoalkylderivatives, having the formula: ##STR4## wherein: n is 1 or 0;

R₁ is hydrogen, lower alkyl, aryl, or aralkyl;

R₂ is hydrogen or lower alkyl;

R₃ is hydrogen, lower alkyl or aroyl;

R₅ is hydroxy, amino, or lower alkoxy;

X is hydrogen, hydroxy, lower alkyl, lower alkoxy, or halogen;

Y is hydrogen, lower alkyl, or aryl;

R₄ is ##STR5## wherein: L is O, NR₇ or S (where R₇ is hydrogen or loweralkyl);

M is R₈, OR₈, SR₈, or NR₉ R₁₀ (where R₈ is hydrogen, lower alkyl, aryl,or aralkyl; and R₉ and R₁₀ are, independently, hydrogen, lower alkyl, oraryl);

A is 0,NR₁₃ or S;

R₁₁ and R₁₂ are, independently, hydrogen, alkyl, aralkyl or aryl;

R₁₃ is hydrogen or lower alkyl;

m is 0, 1, 2, or 3;

R₂₀ is hydrogen or aryl; and

R₂₁ is hydroxy or lower alkoxy; or pharmaceutically acceptable saltsthereof.

This invention further concerns 1H, 3H-[1,4]thiazepino-[4,3-a] indolesand 1-H-[1,4]thiazino[4,3-a] indoles having the formula: ##STR6## wheren, R₁, R₂, R₃, X, and Y are the same as defined for Formula I.

The compounds of Formulas I and II (and disulfides of I) act asinhibitors of angiotensin converting enzyme and are useful as agents forthe treatment of hypertension and for the study of therenin-angiotensin-aldosterone system of warm-blooded animals. Alsowithin the scope of the invention are methods of treatment ofhypertension utilizing the compounds of the invention, processes for thepreparation of the compounds, and intermediate compounds.

As used herein, "lower alkyl" and "lower alkoxy" refer to groups havingup to 4 carbon atoms. "Aryl" refers to phenyl or phenyl substituted by ahalogen, lower alkyl, or lower alkoxy group. "Aralkyl" refers to benzylor benzyl substituted as above for phenyl. "Aroyl" refers to benzoyl orbenzoyl substituted as above for phenyl. Halogen refers to chlorine,bromine and fluorine.

BACKGROUND OF THE INVENTION

In pharmacological research on hypertension, recent attention hasfocused on the study of the renin-angiotensin-aldosterone system, and,in particular, on the development of an effective anti-hypertensiveagent which would, theoretically, achieve its result by inhibiting theaction of angiotensin converting enzyme in converting antiogensin I toangiotensin II. The inhibition of the production of angiotensin IIbecame important because of the discoveries of that angiotensin II isthe most potent pressor agent (vasoconstrictor) present in the mammalianbody and, in addition, stimulates the adrenal cortex to releasealdosterone, thereby causing excessive sodium retention and fluidretention, contributing further to the hypertensive state. Thus,inhibiting the conversion of angiotensin I to angiotensin II is believedto work directly on the primary biochemical mechanisms creatingincreased blood pressure. For a description of the mechanisms and of themammalian renal-angiotensin-aldosterone system, see Hypertension, Genestet al., ed., Chapters 6.1, 6.2, 7.1, 7.2, and 7.3 (McGraw Hill, 1977)and John H. Laragh, "The Renin System in High Blood Pressure, FromDisbelief to Reality: Converting-Enzyme Blockade for Analysis andTreatment", Prog. in Cardio. Vasc. Disease, XXI, No. 3, 159-166(November, 1978).

An extensive list of angiotensin converting enzyme inhibitors is setforth in Suzanne Oparil's article entitled "Angiotensin I ConvertingEnzyme and Inhibitors" in Genest et al., supra, Chapter 6.3, at pp.159-161. These inhibitors are summarized in Table I, p. 161, thereof andinclude chelating agents, sulfonylating agents, heavy metal ions,sulfhydryl binding reagents, and various peptides. The polypeptidesdescribed therein as angiotensin converting enzyme inhibitors includehormones, such as bradykinin; products of substrate digestion such asHis-Leu, Phe-Arg, and Arg-Pro-Pro; and various snake venom polypeptideextracts. Two of the most potent and most studied inhibitors are theBothrops jararaca snake venom extract, the pentapeptide(Pyr-Lys-Trp-Ala-Pro), also referred to as BPP_(5a), and the nonapeptide(Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro), also referred to as BPP_(9a).(BPP stands for Bradykinin Potentiating Peptide). BPP_(9a) has beenshown to be an effective anti-hypertensive agent in clinical studies onhumans with certain forms of hypertension. However, BPP_(9a) is notorally active as an anti-hypertensive agent. For a summary of theclinical aspects of BPP_(9a) see Genest et al., supra, Chapter 6.3, pp.163-4.

More recently, a series of proline derivatives has been found to besignificantly more potent as inhibitors of angiotensin converting enzymeand as anti-hypertensive agents than BPP_(9a). Of these prolinederivatives, D-3-mercapto-2-methylpropanoyl-L-proline has been reportedto be the most effective, including being effective when administeredorally. These proline and mercaptoproline derivatives and variouspharmacological test results thereon are described in Cushman et al.,"Design of New Anti-hypertensive Drugs: Potent and Specific Inhibitorsof Angiotensin Converting Enzyme", Prog. in Cardio. Diseases, Vol. XXI,No. 3 (Nov./Dec., 1978), and in U.S. Pat. Nos. 4,046,889 and 4,105,776,both to Ondetti and Cushman.

DETAILED DESCRIPTION OF THE INVENTION

The generic description of the compounds of the invention is given aboveby Formulas I and II. A preferred group (IC) of compounds of Formula Iare those in which R₃ is hydrogen or lower alkyl; and R₄ is --SH or##STR7## wherein L is O, NR₇ or S (where R₇ is hydrogen or lower alkyl);and

M is R₈, OR₈, SR₈, or NR₉ R₁₀ (where R₈ is hydrogen, lower alkyl, arylor aralkyl; and R₉ and R₁₀ are, independently, hydrogen, lower alkyl, oraryl).

Another preferred group (ID) of compounds of Formula I are those inwhich R₄ is ##STR8## wherein: m is 0, 1, 2, or 3;

R₁₃ is hydrogen or lower alkyl;

R₂₀ is hydrogen or aryl; and

R₂₁ is hydroxy or lower alkoxy.

Preferred compounds of the latter group (ID) are those in which R₁₃ ishydrogen; m is 2; R₂₀ is phenyl; Y is hydrogen; X is hydrogen; or R₂ ishydrogen. Particularly preferred compounds of this group (ID) are thosein which m is 2, R₁₃ is hydrogen, R₂₀ is phenyl and R₂₁ is ethoxy, orhydroxy.

Further preferred compounds of Formula I include those in which Y ishydrogen, lower alkyl, or aryl; R₁ is hydrogen or lower alkyl; R₄ isthiol or arylcarbonylthio; n is 1; n is 1 and R₂ and R₃ are hydrogen; nis 0 and R₂ is hydrogen; and R₅ is hydroxy. Particularly preferredcompounds of Formula I include those in which X is hydrogen; Y ishydrogen; R₁ is lower alkyl; R₄ is thiol or benzoylthio; n is 1, R₁ islower alkyl, and R₂ and R₃ are hydrogen; and n is O, R₁ is lower alkyl,and R₂ is hydrogen. A particularly preferred compound of Formula I isthe compound of Example 40.

As preferred group of compounds of Formula II are those in which R₃ ishydrogen or lower alkyl. Further preferred compounds of Formula IIinclude those in which Y is hydrogen, lower alkyl, or aryl; R₁ ishydrogen or lower alkyl; n is 1; n is 1 and R₂ and R₃ are hydrogen; andn is 0 and R₂ is hydrogen. Particularly preferred compounds of FormulaII include those in which X is hydrogen; Y is hydrogen; R₁ is loweralkyl; n is 1, R₁ is lower alkyl, and R₂ and R₃ are hydrogen; and n is0, R₁ is lower alkyl, and R₂ is hydrogen.

Where either Y or R₃ of Formula I or II is other than hydrogen, thecarbon atom to which it is attached is an asymmetric carbon atom.Similarly, where R₁ and R₂ are different, the carbon atom to which theyare attached is an asymmetric carbon atom. Additionally, the carbon atomdesignated 2 in Formula I and the carbon atom designated 11a in FormulaIIa below and the carbon atom designated 10a in Formula IIb below areasymmetric. ##STR9## Where R₄ is --NR₁₃ --CH(COR₂₁)(CH₂)_(m) --R₂₀, thecarbon atom to which the --COR₂₁ group is attached is asymmetric. Thus,the compounds of the invention (including intermediate compounds) existin stereoisomeric forms or in racemic mixtures thereof, all of which arewithin the scope of the invention.

The following compounds of Formula IIa are preferred: The compounds inwhich X, Y, R₂ and R₃ are hydrogen and R₁ is methyl, which is 11,11a-dihydro-4-methyl-1H,3H-[1,4]thiazepino-[4,3-a]indole; and thecompound in which X, Y, R₁, R₂, and R₃ are hydrogen, which is11,11a-dihydro-1H,3H[1,4]thiazepino[4,3-a]indole.

The following compounds of Formula IIb are preferred: The compound inwhich X, Y, and R₂ are hydrogen and R₁ is methyl, which is10,10a-dihydro-3-methyl-1H-[1,4]thiazino[4,3-a]indole; and the compoundin which X, Y, R₁, and R₂ are hydrogen, which is10,10a-dihydro-1H-[1,4]thiazino[4,3-a]indole.

Also within the scope of the invention are the intermediate compounds ofthe formula: ##STR10## wherein: R₁ is hydrogen, lower alkyl, aryl, oraralkyl;

R₁₅ is hydrogen or lower alkyl;

X is hydrogen, hydroxy, lower alkyl, lower alkoxy, or halogen;

Y is hydrogen, lower alkyl, or aryl; and

Z is a carboxylic acid protecting group; or salts thereof.

Further within the scope of the invention are the intermediate compoundsof the formula: ##STR11## wherein: R₁ is hydrogen, lower alkyl, aryl, oraralkyl;

R₁₅ is hydrogen or lower alkyl;

R₅ is hydroxy, amino, or lower alkoxy;

X is hydrogen, hydroxy, lower alkyl, lower alkoxy, or halogen; and Y ishydrogen, lower alkyl, or aryl; or salts thereof.

Further intermediates within the scope of the invention are those formedby the reaction of the reactants of the Formula VII with the startingmaterials III, which are represented by the formula: ##STR12## wherein:

n, X, Y, R₁, and R₂ are as previously defined; R₅ is hydrogen, loweralkyl, or aroyl; R₁₄ is R₅ or OZ (where R₅ and Z are as previouslydefined); and W is bromine, chlorine, or iodine. Those skilled in theart would also appreciate that W may be tosyloxy. R₃ is preferablyhydrogen or lower alkyl.

Also included in the scope of the invention are the dimers (disulfides)of the compounds of Formula I in which R₄ is --SH. These compounds maybe formed during the synthesis of the parent mercapto compound or may bemade from the mercaptan by known methods.

The following flow diagram shows the general method of preparation ofthe compounds of the invention in which n is 1, R₂ is hydrogen, and R₅is hydroxy. ##STR13## where X, Y, R₁, and R₈ are as defined above and Zis a carboxylic acid protecting group (including a lower alkyl group).

The preparation of the starting material (III) is described by Corey etal., J. Am. Chem. Soc., 92, 2476-2488 (1970). The desired X and Ysubstituents may be obtained on starting material III in a manner knownto those skilled in the art.

The compounds of the invention in which R₅ is an amino group may beobtained from the appropriately substituted 2,3-dihydro indole,2-carboxylic acid or ester in a known manner. Where the startingmaterial III then represents the amide or where the carboxylic acidprotecting group (Z) is the desired lower alkyl group, the deprotectionstep (B) is not required. In such cases, R₅ is as desired in the endproduct.

In step A of Chart I, the protected compound III is reacted with anacryloyl of the formula R₁₅ HC═CR₁ COR₁₆ (VI) wherein R₁ and R₁₅ are asdefined above and COR₁₆ is an activated carboxyl group such as an acylhalide, an active ester, or mixed anhydride. The acyl halide group ispreferred. This reaction is run in an inert organic solvent, such asether or methylene chloride, in the presence of an acid scavenger, suchas triethylamine, where an acid is formed during the reaction.

Alternately, in step A, a substituted alkyl acyl compound of the formulaBr(CHR₃)_(n) CR₁ R₂ COR₁₆ (VII) wherein n, R₁, R₂, R₃, and R₁₆ are aspreviously defined, may be reacted with the starting material (III). Inthis procedure, the carboxylic acid group need not be protected, andstep B may, therefore, be eliminated. Use of this route (i.e. utilizingreactant VII in step A) allows the preparation of all the compounds ofthe invention with respect to n, R₁, R₂, and R₃.

The carboxylic acid protecting group may be chosen from any knowncarboxylic acid protecting, for example, methyl, ethyl, and t-butylesters and various amide groups. Various carboxylic acid protectinggroups and their use as described in McOmie, ed., Protective Groups inOrganic Chemistry, Chapter 5 (Plenum Press, 1973). An appropriateprotective group should be selected on the basis that (1) the reagent bywhich it is introduced does not react with another part of the molecule;(2) the protective group does not interfere with subsequent reactions;and (3) the process by which it is removed does not effect otherportions of the molecule.

In step B of Chart I, the carboxyl group is deprotected. For removal ofan alkyl protecting group by hydrolysis treatment of the intermediateIV, first, with an aqueous dimethylsulfoxidepotassium hydroxidesolution, followed by treatment with a dilute mineral acid, such ashydrochloric or sulfuric acid, is a convenient method. Other methods fordeprotecting carboxylic acid groups are described in the literature,e.g. in McOmie, Id.

In step C, the thio group R₄ of the formula ##STR14## [wherein L is O,NR₇ or S (where R₇ is hydrogen or lower alkyl); and M is R₈, OR₈, SR₈,or NR₉ R₁₀ (where R₈ is hydrogen, lower alkyl, aryl, or aralkyl; and R₉and R₁₀ are, independently, hydrogen, lower alkyl, or aryl)] is coupledto the side-chain of the intermediate compounds (V) or to theintermediate compounds (VIII) resulting from the reaction of thestarting material III with the reactant VII. The reactants utilized instep C to form the desired R₄ thio group (except where R₄ is --SH) arethio acids and thiols. These form a thioacyl or thio group by additionto the third carbon atom of the alkene side-chain (intermediates V) orby substitution for the bromine at the second or third carbon atom ofthe side-chain where the reactant VII was used. These reactions may takeplace in an inert organic solvent, such as methylene chloride, THF, ordioxone.

In order to form the compounds of the invention of Formula I in which R₄is SH, a thiobenzoyl compound is preferably formed in step C and removedby hydrolysis or ammonolysis in step D. Such ammonolysis may beaccomplished by first treating the appropriate intermediate Ia with amethanolic ammonia solution and thereafter treating the resultantproduct with acid, such as HCl, to a pH of about 2.

In order to form the compounds of Formula II of the invention, athioester cyclization of the mercapto compounds of Formula I isutilized. The formation of these thiolactones (i.e. the 1H,3H-[1,4]thiazepino[4,3-a]indoles and 1-H-[1,4]thiazino[4,3-a]indoles ofFormula II) can be accomplished by a coupling reagent used widely in thepeptide synthesis, such as dicyclohexylcarbodiimide (DCC) orN-ethyl-N'-(3-dimethylaminopropyl)carbodiimide and related reagents.Example of such reagents are found in pp. 116-121 "Peptide Synthesis"(2nd Ed.) by M. Bodanszky, Y. S. Kalusner, and M. A. Ondetti, WileyInterscience Publication, New York, 1976. The presence of small amountsof 4-dimethylaminopyridine is used to accelerate the reaction andincrease the yield. The preferred reagent for the reaction is DCC in thepresence of 4-dimethylaminopyridine used at room temperature for severalhours in a methylene chloride medium. The same thioester cyclizationscan be accomplished by treatment of the reactants with diethylphosphocyanidate (DEPC) or diphenyl phosphorazidate (DPPA) indimethylformamide in the presence of triethylamine [Yamada et al., J.Org. Chem., 39, 3302 (1974)], or by means of carbonyldiimidazole orcarbonyl-di-1,2,4-triazole [Gais, Angew, Chem. Int. Edit. Engl., 16, 244(1977)].

It will be appreciated that the various compounds of Formula Ia in whichR₄ is ##STR15## (where L and M are as defined above) are intermediatesuseful in the preparation the mercapto compounds of Formula Ib (where R₄is --SH).

The step A alternate procedure may be used to produce the compounds inwhich R₄ is --APO(OR₁₁)(OR₁₂) (X). Thus, the compounds in which A isNR₁₃ may be made by first reacting an amine of the formula H₂ NR₁₃ withthe appropriate intermediate of Formula VIII to form a furtherintermediate of the formula N-[HNR₁₃₋ (CHR₃)_(n) --CR₁ R₂ --CO]--B (XI),where B is the desired 2,3-dihydro-1H-indole carboxylic acid (suitablyprotected) starting material. Intermediate XI may then be reacted with achlorophosphate of the formula ClPO(OR₁₁)(OR₁₂)[where R₁₁ and R₁₂ arenot hydrogen] (XII) to form the desired substituted amino phosphate endproduct. To form such end product where one or both of R₁₁ and R₁₂ ishydrogen requires appropriate selection of R₁₁ and R₁₂ to resist or beamenable to later catalytic hydrogenolysis. Where A is S in Formula X,the compounds of the invention may be made by reacting amercaptophosphate of the formula HSPO(OR₁₁)--(OR₁₂) (XIII) directly withthe appropriate intermediate of Formula VIII. In order to make thosecompounds of the invention in which A of Formula X is O, an intermediateof the Formula N--[HO--(CHR₃)_(n) --CR₁ R₂ --CO]--B (XIV), where thecarboxylic acid group of B is protected, is formed from the appropriateintermediate of Formula VIII and, then, reacted with the appropriatechlorophosphate of Formula XII (with subsequent hydrogenolysis wherenecessary to obtain R₁₁ or R₁₂ as hydrogen). In order to make thosecompounds of the invention in which A is O and R₁₂ is H in Formula X,the appropriate intermediate of the Formula XIV may be reacted with anappropriate chlorophosphate of Formula XII in the presence of a base,such as pyridine or triethylamine. Again, where R₁₁ or R₁₂ is hydrogenis desired, this reaction will have to be followed by a catalytichydrogenolysis. The reactants and reaction conditions utilized informing the intermediates for and final products of those compounds ofthe invention in which R₄ is APO(OR₁₁)(OR₁₂) (X) are known to thoseskilled in the art. Further description of such methods of preparationmay be found in European Patent No. 9-183 to Merck & Company Inc., datedApr. 2, 1980 (Derwent No. 25743C/15).

Compounds in which R₄ is --NR₁₃ CH(COR₂₁)(CH₂)_(m) R₂₀ may be preparedfrom intermediate XI by condensation with compounds of the formulaeBrCH(COR₂₁)(CH₂)_(m) --R₂₀ (XV) or R₂₁ OC--CO--(CH₂)_(m) --R₂₀ (XVI).When XV is the reactant, conditions fostering nucleophic displacementmay be used (for example, a polar solvent such as dimethyl formamide inthe presence of a base, with or without the addition of catalyticquantities of potassium iodide). When XVI is the reactant, conditionsfostering reductive alkylation may be employed. For example XI may becondensed with XVI in a solvent in the presence of hydrogen and ahydrogenation catalyst according to the general procedures described inW. E. Emerson, Organic Reactions IV, 174 (1948). Alternatively XI may becondensed reductively with XVI in an acidic buffered solvent with analkali metal cyanoborohydride. General procedures for such condensationsare described in R. F. Borch, M. D. Bernstein and H. D. Durst, J. Am.Chem. Soc., 93 2897 (1971). When R₃ is aroyl, the nucleophilicdisplacement type condensation is preferred.

A preferred method of making optically active1-(S)-2,3-dihydro-1-[(S)-3-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid, the 3-benzoylthio precursor thereof, or the dicyclohexylaminesalts of the latter comprises the following steps:

(a) Preparing 1-3-benzoylthio-2-methyl propionyl chloride by admixing1-3-benzoylthio-2-methyl propionic acid with thionyl chloride in thepresence of a catalytic amount of trialkylamine at room temperature andevaporating the volatile components in vacuo,

(b) Condensing the said propionyl chloride withd,l-2,3-dihydro-1H-indole-2-carboxylic acid in a water immisciblesolvent solution in the presence of two equivalents of trialkylamine at0°-10° for 2-15 minutes and room temperature for 1-5 hours,

(c) Isolating the crude condensation product by acidification,extraction, dehydration and evaporation,

(d) Precipitating1-(S)-2,3-dihydro-1-[(S)-3-benzoylthio-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid dicyclohexylamine salt from an acetonitrile solution by theaddition of dicyclohexylamine to an acetonitrile solution of the saidcrude condensation product.

(e) Optionally recrystallizing said dicyclohexylamine salt from a loweralkanol,

(f) Regenerating the1-(S)-2,3-dihydro-1-[(S)-3-benzoylthio-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid by acidification with potassium hydrogen sulfate, extraction with awater immiscible solvent, dehydration and evaporation, and

(g) Cleaving the benzoyl-thio bond by contacting, in an inertatmosphere,1-(S)-2,3-dihydro-1-[(S)-3-benzoylthio-2-methyl-1-oxopropyl]-1H-indolecarboxylic acid with an alkoxy lower alkyl amine, such as2-methoxyethylamine, followed by acidification, extraction into a waterimmiscible solvent, dehydration and evaporation to give the desired1-(S)-2,3-dihydro-1-[(S)-3-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid, which can be further purified by recrystallization from ethylacetate-hexane.

The starting l-3-benzoylthio-2-methyl propionic acid may be obtained bya resolution of the racemic acid by formation of a salt withdehydroabietylamine followed by acidification. The startingd,l-2,3-dihydroindole-2-carboxylic acid is described in the literature.

The compounds of this invention form basic salts with various inorganicand organic bases which are also within the scope of the invention. Suchsalts include ammonium salts, alkali metal salts like sodium andpotassium salts (which are preferred), alkaline earth metal salts likethe calcium and magnesium salts, salts with organic bases, e.g.,dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, hydrabaminesalts, salts with amino acids like arginine, lysine and the like. Thenon-toxic, physiologically acceptable salts are preferred, althoughother salts are also useful e.g., in isolating or purifying the product,as illustrated in the examples in the case of the dicyclohexylaminesalt.

The compounds of Formula XI form acidic salts with various inorganic andorganic acids, for example hydrochloric acid methanesulfonic acid(mesylate), and toluenesulfonic acid (tosylate). Such salts are alsowithin the scope of the invention.

The salts are formed in conventional manner by reacting the free acidform of the product with one or more equivalents of the appropriate baseproviding the desired cation in a solvent or medium in which the salt isinsoluble, or in water and removing the water by freeze drying. Byneutralizing the salt with an insoluble acid like a cation exchangeresin in the hydrogen form (e.g., polystyrene sulfonic acid resin likeDowex 50) or with an aqueous acid and extraction with an organicsolvent, e.g., ethyl acetate, dichloromethane or the like, the free acidform can be obtained, and, if desired, another salt formed.

The angiotensin converting enzyme (ACE) inhibitory property of thecompounds is measured in vitro and in vivo. The in vitro assay utilizesrabbit lung extract and a specific tripeptide substrate,hippuryl-L-histidyl-L-leucine being preferred, and follows the method ofCushman et al., Biochem. Pharmacol., 20, 1637-1648 (1971).

The in vivo ACE inhibitory activity of the compounds is measuredaccording to the procedure described in Rubin et al., J. Pharmacol. Exp.Ther., 204, 271-280 (1978), which utilizes the conscious normotensivetat as a subject. In this procedure, the jugular vein and carotid arterycannulae are placed in an etheranesthetized, normotensive, male,Sprague-Dawley rat for injection or oral dosage of compounds and directrecording of systemic arterial pressure, respectively. The bloodpressure responses to I. V. injections of angiotensin I (300 ng/kg.),angiotensin II (100 ng/kg.) and bradykinin (10 μg/kg.) are recorded andcompared with identical doses administered at various time intervalsafter oral dosing of a prospective angiotensin converting enzymeinhibitor. An angiotensin converting enzyme inhibitor would not beexpected necessarily to lower arterial pressure in the normotensive rat,but would be expected to block angiotensin I pressor responses withoutgrossly altering angiotensin II responses. Additionally, thevasodepressor response to bradykinin would be expected to be augmentedsince angiotensin converting enzyme is known to inactivate bradykininnormally.

When administered orally and intravenously according to this procedure,compounds of Formulas I and II (and disulfides) showed an ability toinhibit angiotensin converting enzyme at doses of 0.1-10 mg/kg.

The anti-hypertensive effect of the compounds of the invention ismeasured in the spontaneously hypertensive rat. In this proceduresystolic pressure of male spontaneously hypertensive rats is measured byan indirect technique using the Decker Caudal Plethysmograph or otherappropriate sensor. Groups usually consist of 4 or more rats. Drugs areusually administered orally. Pressures are usually read prior to drugadministration and at 1.5, 4 and 24 hours thereafter. This schedule maybe altered depending upon the behavior of the drug.

This procedure measures the hypotensive effect of the subject compoundsin a hypertensive subject using a single dose and measuring the responseover a 24 hour period. When administered orally according to thisprocedure, compounds of the invention produced a significant decrease inblood pressures in doses of 1-50 mg/kg. When used to treat hypertensionin warm-blooded animals doses of less than 15 mg/kg./day would beutilized, and preferably doses of less than 5 mg/kg./day. Such effectivetreatment doses would generally be administered in long-termantihypertensive therapy. Angiotensin converting enzyme inhibitors whenutilized as anti-hypertensive agents are most effective upon suchextended administration and exhibit no significant sideeffects whenadministered at moderate or low doses. As noted earlier, the compoundsof the invention exhibit a hypotensive (depressor) response only whenadministered to hypertensive subjects and would not be expected to lowerblood pressures significantly in normotensive subjects.

The compounds of Formulas I and I (and the disulfides of Formula Icompounds) may be administered orally, intravenously, intraperitoneally,intramuscularly, or subcutaneously. Oral administration is preferred.

When employed to lower blood pressures in hypertensive subjects, theeffective dosage of the compound being utilized for such treatment willvary according to the particular compound being employed, the severityand nature of condition being treated, and the particular subject beingtreated. Therapy should be initiated at lower doses (in mg/kg./day) inthe effective ranges given above, the dosage thereafter being increased,if necessary, to produce the desired anti-hypertensive effect.

Futher, when employed as anti-hypertensive agents or as angiotensinconverting enzyme inhibitors, the compounds of the invention may beadministered alone or in combination with pharmaceutically acceptablecarriers. The proportion and nature of such carriers would be determinedby the solubility and other chemical properties of the compoundselected, the chosen route of administration, and standardpharmaceutical practice.

As previously noted, this invention also includes methods of treatmentof hypertension in warm-blooded animals utilizing hypotensivelyeffective amounts of the compounds of Formulas I and II (and thedisulfides of the Formula I compounds in which R₄ is --SH). The genericand subgeneric aspects of this part of the invention encompass the samecompounds and groups of compounds described above with respect to thecompound portion of the invention.

The compounds of Formula XI are among the intermediates for which patentprotection is sought. These compounds have the formula (described onpage 13 above): ##STR16## wherein X, Y, R₁, R₂, R₃, R₁₃, R₁₄ and n areas previously defined. Preferred compounds of Formula XI are those inwhich n is O; R₂ is hydrogen; R₁₃ is hydrogen; X is hydrogen; Y ishydrogen; or R₁ is lower alkyl. Particularly preferred compounds of thisaspect of the invention are those in which n is O, R₂ and R₁₃ arehydrogen and R₁ is lower alkyl.

The methods of making and using the compounds of the invention and thebest mode of the invention are further illustrated in the followingexamples:

EXAMPLE 12,3-Dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acidethyl ester

To a chilled and stirred mixture of 2,3-dihydroindole-2-carboxylic acidethyl ester (4.78 g., 25.0 mmole), triethylamine (2.7 g., 26.7 mmole),and anhydrous ether (500 ml) was added dropwise methacryloyl chloride(2.9 g., 27.7 mmole) dissolved in a small amount of ether. After thecompletion of the addition, the ice bath was removed, and the reactionmixture was stirred for 4 hours. The precipitate which separated wasremoved by filtration, and the filter residue was washed with ether. Thecombined filtrate and washing were washed with water (two 700-mlportions), then with saline, and dried over anhydrous magnesium sulfate.Evaporation of the solvent under reduced pressure on a rotary evaporatorgave the product as an oil. The product was purified by preparative HPLC(Prep LC/System 500, Waters Associates), using a micro porasil columneluted with a mixture of hexane (95%) and ethyl acetate (5%). The crudeoil may be used directly in the following reaction (Example 2).

EXAMPLE 22,3-Dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acid

A mixture of2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acidethyl ester (3.9 g., 15.0 mmole), 80% aqueous dimethylsulfoxide (90 ml.)and potassium hydroxide (86% pellets, 1.3 g., 19.9 mmole), was stirredunder nitrogen atmosphere for 2 days at room temperature, thenevaporated under reduced pressure on a rotary evaporator to give an oilyresidue. The residue was dissolved in water (any insolube material wasremoved by filtration), and the aqueous solution was made acidic bycareful addition of dilute hydrochloric acid, whereby an oil separated.The oily product was extracted with ether, and the ether extract waswashed with water (3 times), then with saline. The ether solution wasdried over anhydrous magnesium sulfate, and evaporated under reducedpressure to give an oily product. The oil was dissolved in dryacetonitrile, and dicyclohexylamine was added dropwise until the pH ofthe solution reached approximately 8.5. A crystalline precipitate wasfiltered. The mixture was allowed to stand overnight at roomtemperature, and the precipitate was collected on a filter, and thefilter residue was washed with ether several times to give 3.46 g. of2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic aciddicyclohexylamine salt (m.p. 185°-190°). Recrystallization from2-propanol gave 3.1 g. (50.0%) of the title product as thedicyclohexylamine salt (m.p. 193°-195°) [m.p. means melting point indegrees centigrade, uncorrected.]

Analysis for: C₂₅ H₃₅ N₃ O₃. 1/4 H₂ O: Calculated: C, 72.16; H, 8.60; N,6.73. Found: C, 72.05; H, 8.83; N, 6.64.

The salt was partitioned between 5% aqueous potassium bisulfate solution(50 ml.) and ethyl acetate (3 times), and the ethyl acetate extract waswashed with water, then dried over anhydrous magnesium sulfate.Evaporation of the ethyl acetate solution under reduced pressure on arotary evaporator afforded 1.8 g. of free2,3-dihydro-1-(2-methyl-1-Oxo-2-propenyl)-1H-indole-2-carboxylic acid inresinous form which solidified on standing. The solid was dissolved inether, and the ether solution was evaporated in open air, whereby aprecipitate separated. The mixture was chilled in ice, and theprecipitate was collected on a filter and washed with ether. The productmelted at 138°-140°.

Analysis for: C₁₃ H₁₃ NO₃ : Calculated: C, 67.52; H, 5.67; N, 6.06.Found: C, 67.15; H, 5.75; N, 5.76.

EXAMPLE 31-(3-Benzoylthio-2-methyl-1-oxopropyl)-2,3-dihydro-1H-indole-2-carboxylicAcid

A. Thiobenzoic acid (95%, 0.75 g., 5.2 mmole) dissolved in dry methylenechloride (ca. 3 ml.) was added to a solution of2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acid(1.2 g., 5.2 mmole) in dry methylene chloride (25 ml.) chilled in an icebath. The ice bath was removed, and the reaction was stirred at roomtemperature for 0.5 hr. The reaction mixture was then immersed in an oilbath maintaining the temperature of 85±5° for 3 hrs., and evaporatedunder reduced pressure using a rotary evaporator to give a resinousresidue. Addition of a small amount of ethanol to the residue caused apartial solidification of the residue. The solid material was separatedby filtration, and recrystallized from ethanol to give 0.4 g. (21%) of aproduct which melted at 187°-188°. Analytical sample which was obtainedby recrystallization from ethanol melted at 188°-190°. Thin-layerchromatography carried out on a Merck silica gel plate using a mixtureof methylene chloride (8), ethanol (2), triethylamine (1), and toluene(1) showed one spot with R_(f) 0.7.

Analysis for: C₂₀ H₁₉ NO₄ S: Calculated: C, 65.02; H, 5.18; N, 3.79.Found: C, 64.63; H, 5.27; N, 3.69.

B. The mother liquors from the above recrystallizations were evaporatedto give a resinous material. The residue was dissolved in ether, and theether solution was evaporated under a slow nitrogen stream to cause acrystalline material to be deposited. The crystalline deposit wasfiltered and recrystallized from ether to give 0.5 g. (25%) of theproduct containing a 1/4 mole of ether solvate, m.p. 116°-117°. Thisproduct is the racemic diastereoisomer of the material that melted at188°-190° (Example 3A). Thin-layer chromatography carried out on a Mercksilica gel plate using a mixture of methylene chloride (8), ethanol (2),triethylamine (1), and toluene (1) as a developing solution showed onespot with R_(f) 0.6.

Analysis for: C₂₀ H₁₉ NO₄ S. 1/4 Et₂ O: Calculated: C, 65.01; H, 5.59;N, 3.61. Found: C, 64.71; H, 5.51; N, 3.32.

EXAMPLE 4 2,3-Dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylic acid

A mixture of1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid (Example 3A, m.p. 188°-190°) (0.6 g., 1.6 mmole) and methanolicammonia (5.5N solution, 9 ml.) was stirred at room temperature for 2.5hours, then evaporated under reduced pressure on a rotary evaporator togive a resinous material. The residue was dissolved in water, and thenthe aqueous solution was washed with ether three times. The aqueouslayer was made acidic by dropwise addition of dilute hydrochloric aciduntil pH of the solution reached approximately 2 (by a pH paper). Theoil thus separated was extracted with ethyl acetate (twice) and theethyl acetate extract was washed with water, then with saline, and driedover anhydrous magnesium sulfate. Evaporation of ethyl acetate on arotary evaporator under reduced pressure, then in vacuo gave an oil. Theresidue was dissolved in dry acetonitrile, and dicyclohexylamine wasadded dropwise until pH of the solution reached ca. 8.5. The resultingmixture was kept at room temperature for 2 hours, then in a cold roomfor ca. 0.5 hour. The precipitate that separated was collected on afilter, and washed with acetonitrile to give2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid, dicyclohexylamine salt (yield, 0.63 g., m.p. 203°-205°). Themelting point of a mixture of this salt and the DCHA salt of Example 5was depressed.

Analysis for: C₂₅ H₃₈ N₂ O₃ S: Calculated: C, 67.22; H, 8.58; N, 6.27.Found: C, 66.88; H, 8.33; N, 6.29.

The salt (0.6 g.) was added to 5% aqueous potassium bisulfate solution(10 ml.), and was shaken vigorously. The free acid thus formed wasextracted with ethyl acetate (17 ml. in 2 times). The extract was washedsuccessively with water and saline, and dried over anhydrous magnesiumsulfate. Evaporation of ethyl acetate on a rotary evaporator underreduced pressure afforded a glassy residue. The residue was dissolved ina small amount of ether and the ether solution was added dropwise, undervigorous stirring, to a large volume of hexanes chilled in ice. Thefluffy white precipitate that separated was collected on a filter, anddried in vacuo, giving 0.12 g. of2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid.

Analysis for: C₁₃ H₁₅ NO₃ S: Calculated: C, 58.84; H, 5.70; N, 5.28.Found: C, 59.24; H, 5.95; N, 5.16.

EXAMPLE 52,3-Dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1-H-indole-2-carboxylicacid

A mixture of1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylic(Example 3B, m.p. 116°-117°) isolated with a 1/4 mole of ether from themother liquor of Example 3A (1.0 g., 2.6 mmole) and methanolic ammonia(5.5N solution, 100 ml.) was stirred at room temperature for 2.5 hoursthen evaporated under reduced pressure on a rotary evaporator to give aresinous material. The residue was dissolved in water (20 ml.), and theaqueous solution was made alkaline by addition of five drops of 2Naqueous sodium hydroxide solution. The alkaline solution was washed withether three times, then was made acidic by addition of dilutehydrochloric acid. The oily product thus separated was extracted withether (110 ml. in 3 times). The ether extract was washed with water,then with saline, and dried over anhydrous magnesium sulfate.Evaporation of ether under reduced pressure on a rotary evaporator gavea resinous material which was dissolved in acetonitrile (15 ml.). Thedropwise addition of dicyclohexylamine (ca. 0.65 g.) to the acetonitrilesolution under stirring until pH of the solution reached 8.5 (by a pHpaper), and subsequent cooling in a cold room overnight causedseparation of2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid, dicyclohexylamine salt as a precipitate. The precipitate wascollected on a filter and washed with acetonitrile to give 1.0 g. ofmaterial which melted at 190°-193°. Recrystallization from 2-propanolimproved the melting point to 193°-195°. The melting point of a mixtureof this salt and the DCHA salt of Example 4 compound was depressed.

Analysis for: C₂₅ H₃₈ N₂ O₃ S: Calculated: C, 67.22; H, 8.58; H, 6.27.Found: C, 67.09; H, 8.58; N, 6.33.

The salt (0.744 g.) was added to 5% aqueous potassium bisulfate solution(10 ml.), and was shaken vigorously. The free acid thus formed wasextracted with ethyl acetate (25 ml. in 2 times). The extract was washedsuccessively with water and saline, and dried over anhydrous magnesiumsulfate. Evaporation of ethyl acetate on a rotary evaporator underreduced pressure afforded a glassy residue. The residue was dissolved in25 ml. of ether, and the ether solution was added dropwise undervigorous stirring to a large volume of hexanes (300 ml.) chilled in ice.The white solid precipitate which separated was collected on a filter,and washed with hexanes, giving 280 mg. of the title compound. The massspectrum obtained using a AEI MS 902-kratos DS 50 S spectrometer showedpeaks at m/c 265 (M⁺), 163 and 118.

Analysis for: C₁₃ H₁₅ NO₃ S: Calculated: C, 58.64; H, 5.70; N, 5.28.Found: C, 58.61; H, 5.62; N, 4.88.

EXAMPLE 6 2,3-Dihydro-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acidethyl ester

To a chilled and stirred mixture of 2,3-dihydroindole-2-carboxylic acidethyl ester (14.34 g.), triethylamine (7.65 g.) and anhydrous ether (600ml.) was added dropwise acryloyl chloride (7.1 g.) dissolved in a smallamount of ether. The ice bath was removed, and the reaction mixture wasstirred at room temperature for 4 hours. The reaction mixture waschilled in ice, then a precipitate was removed by filtration. The filterresidue was washed with ether. The combined filtrate and washing werewashed with water, then with saline, and dried over anhydrous magnesiumsulfate. Evaporation of the solvent under reduced pressure on a rotaryevaporator gave the titled compound (14.4 g.) as an oil.

EXAMPLE 7 2,3-Dihydro-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acid

A mixture of 2,3-dihydro-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester (14.4 g.), 80% aqueous dimethylsulfoxide (200 ml.) andpotassium hydroxide (86% pellets, 3.85 g.) was stirred under nitrogenatmosphere for 2.5 days at room temperature, then evaporated underreduced pressure on a rotary evaporator to give an oily residue. Theresidue was dissolved in water with the aide of a small amount of dilutesodium hydroxide solution. The aqueous solution was washed with ethertwice, then made acidic by addition of dilute hydrochloric acid to pHca. 2. The oil thus separated was extracted with ether three times. Thecombined ether extract was washed with water, then with saline, anddried over anhydrous magnesium sulfate. Evaporation of the ether on arotary evaporator under reduced pressure gave a solid residue whichmelted at 158°-160°, and weighed 9.2 g. Recrystallization from ethylacetate improved the melting point to 167°-169°.

Analysis for: C₁₂ H₁₁ NO₃ : Calculated: C, 66.35; H, 5.11; N, 6.45.Found: C, 66.16; H, 5.10; N, 6.33.

EXAMPLE 81-[3-(Benzoylthio)-1-oxo-propyl]-2,3-dihydro-1H-indole-2-carboxylic acid

To a stirring mixture of2,3-dihydro-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acid (6.52 g.)and methylene chloride 160 ml.) was added dropwise thiobenzoic acid(95%, 4.36 g.) dissolved in a small amount of methylene chloride. Duringthe addition, the reaction mixture was chilled in ice. The ice bath wasremoved in 10 minutes after the completion of the addition, but thestirring was continued for 1 hour. The reaction mixture was thenimmersed in an oil bath maintained at 80° for 2.5 hours. The reactionmixture was concentrated on a rotary evaporator under reduced pressureto ca. 30 ml., and kept in a refrigerator for 1 day. A precipitate wascollected on a filter and washed with methylene chloride to give thetitled compound which melted at 173°-175°, and weighed 11.0 g.

Analysis for: C₁₉ H₁₇ NO₄ S: Calculated: C, 64.21; H, 4,82; N, 3.91.Found: C, 64.38; H, 4.93; N, 3.96.

EXAMPLE 9 2,3-Dihydro-1-(3-mercapto-1-oxopropyl)-1H-indole-2-carboxylicacid

A mixture of1-[3-(benzoylthio)-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylic acid(3.0 g.) and methanolic ammonia (5.5N solution, 45 ml.) was stirred atroom temperature for 2.5 hours, then evaporated under reduced pressureon a rotary evaporator to give a resinous material. The residue wasdissolved in water, and the aqueous solution was washed with ethylacetate three times. The aqueous phase was acidified to pH ca. 2 bydropwise addition of dilute hydrochloric acid, whereby an oil separated.The oil was extracted with ethyl acetate (two times). The combinedextract was washed with water, then with saline, and dried overanhydrous sodium sulfate. The ethyl acetate was evaporated on a rotaryevaporator under reduced pressure to give an oily residue which wasplaced under high vacuum to give a solid material. The crude product wasdissolved in a small amount of warm ethyl acetate with warming on asteam bath (there was some insoluble solid material which was removed byfiltration). The ethyl acetate solution was kept under mild nitrogenstream until a precipitate started to separate. The mixture was chilledin ice, then kept in a refrigerator. The precipitate was collected on afilter and washed with acetonitrile to give1,1'-dithiobis-[3-oxo-1,3-propanediyl]bis[2,3-dihydro-1H-indole-2-carboxylicacid], m.p. 213°-216°.

Analysis for: C₂₄ H₂₄ N₂ O₆ S₂ : Calculated: C, 57.58; H, 4.83; N, 5.60.Found: C, 57.56; H, 4.96; N, 5.13.

The mother liquor and washings were combined, and evaporated on a rotaryevaporator under reduced pressure to dryness. The residue was dissolvedin acetonitrile with warming on a steam bath. Dicyclohexylamine wasadded to the solution until pH of the solution reached ca. 8.0 (by a pHpaper). The dicyclohexylamine salt thus formed was collected on afilter, and recrystallized from ethanol. The salt melted at 203°-205°.

Analysis for: C₁₂ H₁₃ NO₃ S: Calculated: C, 66.63; H, 8.39; N, 6.48.Found: C, 66.35; H, 8.14; N, 6.06.

The salt was shaken with 5% aqueous potassium bisulfate solution (70ml.), and the free acid thus separated was extracted with ethyl acetate(70 ml. in two times). The combined extract was washed with water, thenwith saline, and dried over anhydrous sodium sulfate. Evaporation ofethyl acetate on a rotary evaporation under reduced pressure gave asolid residue which was recrystallized from ethyl acetate. The titledcompound melted at 146°-148° dec.

Analysis for: C₁₂ H₁₃ NO₃ S: Calculated: C, 57.35; H, 5.21; N, 5.57.Found: C, 57.39; H, 5.27; N, 5.37.

EXAMPLE 10 Resolution ofd,l-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid intod-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acidand l-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid

A. To a hot vigorously stirred methanolic solution ofd,l-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid of Example 2 (29 g. in 300 ml. of methanol) was added slowly a warmmethanolic solution of dehydroabietylamine (DHAA, 18.9 g. in 60 ml. ofmethanol). The stirring was continued for additional 5 minutes, thenallowed to set at room temperature for 10 minutes. The mixture wasreheated to boiling, and to the hot, vigorously stirred solution wasadded hot water (240 ml.). The reesulting mixture was placed in arefrigerator overnight. The white precipitate that separated wascollected on a filter, and washed with cold aqueous methanolsolution[methanol (300 ml.)/water (250 ml.)] 5 times, givingd-2,3-dihydro-1-(2-methyl-1-oxopropenyl)-1H-indole-2-carboxylic acid,DHAA salt (27.9 g.), m.p. 207°-209° C. The combined filtrate andwashings were set aside for isolation ofl-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H -indole-2-carboxylicacid. Recrystallization of the DHAA salt (filter residue) from methanolimproved the m.p. to 218°-219° C., [2]_(D) ²⁵ =84.24 (c=0.985%, EtOH).

Analysis for: C₁₃ H₁₃ NO₃.C₂₀ H₃₁ N: Calculated: C, 76.70; H, 8.58; N,5.42. Found: C, 76.15; H, 8.53; N, 5.19.

The salt was pulverized with a mortar and pestle and partitioned between1N aqueous sodium hydroxide solution and ether. The aqueous layer wascollected, and washed with ether twice, and acidified with dilutehydrochloric acid. The free acid that separated was extracted with ether3 times. The combined extracts were washed with water, then with salinetwice, and dried over anhydrous sodium sulfate. Evaporation of etherunder reduced pressure gave a solid residue which was recrystallizedfrom ether, givingd-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acid,m.p. 148°-150° C., [α]_(D) ²³.5 =+133.45 (c=1.11%, EtOH).

Analysis for: C₁₃ H₁₃ NO₃ (231.24): Calculated: C, 67.52; H, 5.67; N,6.06. Found: C, 67.36; H, 5.71; N, 5.96.

B. The original combined filtrate and washings (aqueous methanolsolution) were evaporatd carefully on a rotary evaporator under reducedpressure to ca. 120 ml., then placed in a refrigerator overnight. Thesolid material which separated was collected on a filter, washed withcold water, and dried in vacuo. The dried filter residue (18.7 g., m.p.130°-134° C.) was pulverized with a mortar and pestle, and dissolved inwarm anhydrous ether (600 ml.). The supernatant liquid was filteredthrough a course folded filter paper. The insoluble residue was warmedwith anhydrous ether (ca. 300 ml.), and supernatant liquid was combinedwith the original filtrate filtering through the same filter paper. Thisether extraction was repeated two additional times (ca. 200 ml., and ca.100 ml. in each time). The combined ether extracts were allowed to setat room temperature overnight. A small amount of fluffy material thatdeposited was removed by filtration, and the filtrate was concentratedon a rotary evaporator to a slurry. The residue was chilled, andfiltered on a suction filter. The filter residue was washed with coldether to give crudel-2,3-dihydro-1-(2-methyl-1-oxo-2-prophenyl)-1H-indole-2-carboxylic acid(12.3 g., m.p. 140°-143° C.). The crude product was dissolved inanhydrous ether (ca. 600 ml. in 3 portions), filtered, and the filtratewas concentrated to ca. 300 ml. The concentrated solution wasrefiltered, and the filtrate was diluted with hexane until it becamecloudy. The mixture was stored in a freezer overnight. The precipitatethat separated was collected on a filter, and washed with cold ether,giving the l-isomer (10 g.) with m.p. 147°-148° C. and [α]_(D) ²⁵.5=-122.5 (C=0.835, EtOH). Further purification by recrystallization inthe above fashion gavel-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acidwith m.p. 152°-154° C. and [α]_(D) ²⁵ =135.9 (c=0.935, EtOH).

Analysis for: C₁₃ H₁₃ NO₃ : Calculated: C, 67.52; H, 5.67; N, 6.06.Found: C, 67.33; H, 5.68; N, 6.04.

EXAMPLE 11l-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt

To a stirred solution of thiobenzoic acid (95% purity; 8.0 g.) inacetone (450 ml.) under nitrogen atmosphere was added4-dimethylaminopyridine (0.61 g.) The resulting mixture was stirred for5 minutes and thenl-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acid(11.56 g., Example 10 B) was added. The resulting mixture was heatedunder reflux for 6 hours. Evaporation of the acetone in vacuo gave aresinous residue which was dissolved in methylene chloride. Themethylene chloride solution was washed twice with cold 1N hydrochloricacid, twice with saline, and dried over anhydrous magnesium sulfate.Evaporation of methylene chloride solution on a rotary evaporator underreduced pressure gave a foamy resinous material. The residue wasdissolved in dry acetonitrile (250 ml.) and the solution was chilled inice. Dicyclohexylamine (9.2 g.) was added slowly to the coldacetonitrile solution with agitation, and the resulting mixture waschilled for 2 hours. The precipitate was collected on a filter, andwashed with acetonitrile 5 times, then with ethanol repeatedly, givingcrudel-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxo-propyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (17.76 g., m.p. 193°-198° C.). (Thefiltrate and washings were combined, and set aside for isolation ofd-(S)-1-[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]--2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt.) Recrystallization of the crude productfrom ethanol improved the m.p. to 219°-221° C. (yield, 12.13 g.),[α]_(D) ²³ =-69.16 (c=1.035%, EtOH). The sample which melted at222°-224° showed [α]_(D) ²².5 =76.6 (c= 1.135%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 69.78; H, 7.69; N,5.09. Found: C, 69.53; H, 7.73; N, 5.14.

EXAMPLE 12d-(S)-1-[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt

A mixture ofl-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acid(5.78 g. of Example 10 B), thiobenzoic acid (95% purity, 5 g.) andmethylene chloride (70 ml.) was refluxed under nitrogen atmosphere for8.5 hours, then evaporated on a rotary evaporator under reduced pressureto give a resinous residue. The residue was dissolved in acetonitrile(50 ml.) and ca. 5.0 g. of dicyclohexylamine was added dropwise to theacetonitrile solution (pH of the mixture was ca 6.5 when tested by a wetpH paper). The resulting mixture was chilled in a refrigerator for 1.5hours. (The precipitate was collected on a filter, and the filterresidue was washed with acetonitrile, giving crudel-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt as in Example 11.) The combined filtrateand washings were placed in a hood overnight, and chilled in ice. Theprecipitate that separated was removed by filtration, and the motherliquor was treated with an additional amount of dicyclohexylamine untilthe pH of the solution reached 8. The resulting solution wasconcentrated by allowing to evaporate in a hood overnight, then chilledin ice. The precipitate that separated was collected on a filter andwashed with acetonitrile, giving cruded-(S)-[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (7.39 g., m.p. 127°-130°). Purification byrecrystallization from acetonitrile improved the m.p. 132°-134°, [α]_(D)²².5 =+26.00 (c=1.04%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 69.78; H, 7.69; N,5.09. Found: C, 69.83; H, 7.64; N, 5.01.

EXAMPLE 13d-(R)-1-[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt

A mixture ofd-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylic acid(2.31 g., Example 10 A) thiobenzoic acid (95% purity, 1.60 g.), andmethylene chloride (50 ml.) was heated under reflux for 6 hours, thenevaporated on a rotary evaporator under reduced pressure to give aresinous material. The residue was dissolved in acetonitrile andchilled. The cold solution was treated with ca 2.0 g. ofdicyclohexylamine until pH of the mixture became approximately 8.5. Theresulting mixture was chilled in ice for 1.5 hours, and a precipitatewas collected on a filter and washed with acetonitrile, giving cruded-(R)-1-[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (2.65 g., m.p. 201°-204°). (The filtrateand washings were combined, and set aside for isolation ofl-(R)-1[(S)-3-(benzolythio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt.) Recrystallization of the crude productfrom ethanol improved the m.p. to 219°-221° (yield 1.4 g.). Anotherrecrystallization from ethanol gave an analytical sample, m.p.222°-224°, [α]_(D) ²⁵.5 =+70.59 (c=0.975%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 69.78; H, 7.69; N,5.09. Found: C, 69.52; H, 7.64; N, 5.09.

EXAMPLE 14l-(R)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine

After the combined acetonitrile filtrate and washings from Example 13were allowed to set at room temperature for several days, theprecipitate that separated was collected on a filter and was washed withacetonitrile, giving crudel-(R)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (0.94 g., m.p. 131°-133°).

Recrystallization from acetonitrile, then from ethyl acetate improvedthe m.p. to 133°-135°, [α]_(D) ²⁴.5 =-20.18 (c=1.02%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 69.78; H, 7.69; N,5.09. Found: C, 69.96; H, 7.63; N, 5.02.

EXAMPLE 15l-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid

Powderedl-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylic acid, dicyclohexylamine salt*(2.0 g.) was shakenvigorously with a mixture of 5% aqueous potassium hydrogensulfate (50ml.) and ethyl acetate (45 ml.) in a separatory funnel, and the ethylacetate layer was separated. The aqueous layer was extracted twoadditional times with ethyl acetate (20 ml. and 10 ml.) The combinedethyl acetate extracts were washed with water, then with saline, anddried over anhydrous sodium sulfate. Evaporation of the solvent on arotary evaporator under reduced pressure gave an oily residue whichsolidified on standing. Recrystallization from ether and hexanes gavel-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, (1.25 g.), m.p. 144°-146°, [α]_(D) ²⁵ =-183.6 (c=1.07%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S: Calculated: C, 65.02; H, 5.18; N, 3.79.Found: C, 65.03; H, 5.39; N, 3.78.

EXAMPLE 16 d-(S)-1-[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylic acid

The title compound was obtained in resinous form from the correspondingdicyclohexylamine salt of Example 12 (2.5 g.) by the treatment with 5%aqueous potassium hydrogen sulfate solution as described in Example 15.[α]_(D) ²².5 =+65.29 (c=1.145%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S: Calculated: C, 65.02; H, 5.18; N, 3.79.Found: C, 64.90; H, 5.30; N, 3.51.

EXAMPLE 17d-(R)-1[(R)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylic acid

The title compound (0.38 g.) was obtained from the correspondingdicyclohexylamine salt of Example 13 (0.7 g.) by the treatment with 5%aqueous potassium hydrogen sulfate solution as described in Example 15,m.p. 143°-145°, α]_(D) ²⁵.5 =+179.33 (c=1.04%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S: Calculated: C, 65.02; H, 5.18; N, 3.79.Found: C, 64.92; H, 5.32; N, 3.79.

EXAMPLE 18l-(R)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid

The title compound was obtained from the corresponding dicyclohexylaminesalt of Example 14 by the treatment with 5% aqueous potassium hydrogensulfate solution as described in Example 15.

EXAMPLE 19d,l-1-[3-(Acethythio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt

A mixture of2,3-dihydro-1-(2-methyl-1-oxopropenyl-1H-indole-2-carboxylic acid (6.94g.), thioacetic acid (95% purity, 3.9 g.), and methylene chloride (90ml.) was heated under reflux for 5.5 hours, then evaporated on a rotaryevaporator under reduced pressure to give a resinous residue. Theresidue was dissolved in acetonitrile (70 ml.) and chilled in ice.Dicyclohexylamine (ca. 5 g.) was added dropwise to the cold acetonitrilesolution until pH of the solution reached about 8. The resulting mixturewas allowed to set at room temperature for 2 hours, then in arefrigerator for 1 hour. A precipitate was collected on a filter andwashed with acetonitrile 4 times. (The filtrate and washings werecombined, and stored for isolation of the diastereoisomer of the productwhich precipitated first.) Several recrystallizations of the residuefrom ethanol gaved,l-1-[3-(acetylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (2.65 g.) with m.p. 218°-220°.

Analysis for: C₁₅ H₁₇ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 66.36; H, 8.25; N,5.73. C, 66.60; H, 8.08; N, 5.62.

The combined acetonitrile filtrate and washings were concentrated to ca.30 ml., then allowed to set at room temperature for several days. Theprecipitate that separated was collected on a filter, and recrystallizedfrom ethanol several times, givingd,l-1-[3-(acetylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (1.66 g.) with m.p. 201°-203°. The latterproduct is the diastereoisomer of the product which isolated first andmelted at 218°-220°.

Analysis for: C₁₅ H₁₇ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 66.36; H, 8.25; N,5.73. Found: C, 66.41; H, 8.41; N, 5.66.

EXAMPLE 20d,l-1-[3-(acetylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1Hindole-2-carboxylicacid

Treatment ofd,l-1-[3-(acetylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt from Example 19 with a m.p. 218°-220° (1.93g.) with 5% aqueous potassium hydrogen sulfate solution as described inExample 15 afforded the titled compound (0.6 g.) which melted at125°-126°. The product was purified by recrystallizations from ethylacetate and hexane.

Analysis for: C₁₅ H₁₇ NO₄ S: Calculated: C, 58.61; H, 5.58; N, 4.56.Found: C, 58.39; H, 5.59; N, 4.51.

EXAMPLE 21d,l-1-[3-(Acetylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, the racemic diastereoisomer of Example 20

The title compound was obtained fromd,l-1-[3-(acetylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt from Example 19 with m.p. 201°-203° by thetreatment with 5% aqueous potassium hydrogen sulfate solution asdescribed in Example 15. The product, purified by recrystallization fromether and hexane, melted at 94.5°-96°.

Analysis for: C₁₅ H₁₇ NO₄ S: Calculated: C, 58.61; H, 5.58; N, 4.56.Found: C, 58.93; H, 5.66; N, 4.37.

EXAMPLE 22 2,3-Dihydro-5-methoxy-1H-indole-2-carboxylic acid ethyl ester

A three neck 3-liter round bottom flask equipped with a mechanicalstirrer, water condenser, and a gas inlet tube was charged with 500 ml.of absolute ethanol and chilled in a dry ice-acetone bath. Dry hydrogenchloride gas was added at a rapid rate for 0.5 hours. Fifty grams of5-methoxyindole-2-carboxylic acid ethyl ester (B. Heath-Brown and P. G.Philpott, J. Chem. Soc. 1965, 7185) followed by 100 g. of tin metal (30mesh) were added to the solution with stirring. With the dry ice bath inplace, but with no additional cooling the reaction mixture was stirredgently for 6 hours. The crystalline solid that separated was removed byfiltration. The mother liquor was evaporated under reduced pressure togive an oil. The oil dissolved in 500 ml. of absolute ethanol, wasplaced in a 3-liter round bottom flask equipped with a stirrer andthermometer, and chilled to 10°. Gaseous ammonia was bubbled into themixture until the pH was 9 (by wet pH paper) and the mixture was allowedto stand at 10° for one hour. The white precipitate was filtered and thefiltrate was evaporated on a rotary evaporator to dryness. The initialwhite precipitate and the residue from the evaporation were combined andtriturated repeatedly with warm ether. The combined ether triturateswere washed with a sodium chloride solution (a water: saturated saltsolution, 1:1) with vigorous shaking; whereupon most of the basic tinsalts were suspended and separated in the aqueous phase. Both phaseswere filtered through Celite and separated. The ether solution was driedover magnesium sulfate and evaporated under reduced pressure on therotary evaporator. The oily residue was dried in vacuo to give 22 g. ofd,l-2,3-dihydro-5-methoxy-1H-indole-2-carboxylic acid ethyl ester.

Analysis for: C₁₂ H₁₅ NO₃ : Calculated: C, 65.14; H, 6.83; N, 6.33.Found: C, 64.70; H, 6.75; N, 6.32.

EXAMPLE 232,3-Dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester

By substituting 2,3-dihydro-5-methoxy-1H-indole-2-carboxylic acid ethylester for 2,3-dihydro-indole-2-carboxylic acid ethyl ester in theprocedure of Example 1,2,3-dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester was obtained as a thick oil.

Analysis for: C₁₆ H₁₉ NO₄ : Calculated: C, 66.42; H, 6.62; N, 4.84.Found: C, 66.25; H, 6.65; N, 4.70.

EXAMPLE 242,3-Dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid

To a solution of2,3-dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester from Example 23 (8.5 g.) in 45 ml. of reagent-grademethanol was added a solution of 1.32 g. of sodium hydroxide (98%purity) in 16 ml. distilled water with hand swirling. This reactionmixture was stirred at room temperature for 2 hours. With vigorousmechanical stirring, the reaction solution was poured into brine and theslightly turbid mass was acidified with concentrated hydrochloric acid.The resulting mixture was stirred, chilled in an ice-water-salt-bath forone hour and the solids were collected on a sintered-glass funnel andwashed twice with cold water, to give2,3-dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid (7.32 g., m.p. 108°-111°). Recrystallization from ethyl acetateimproved the m.p. to 115°-118°.

Analysis for: C₁₄ H₁₅ NO₄ : Calculated: C, 64.35; H, 5.79; N, 5.36.Found: C, 63.89; H, 5.76; N, 5.22.

EXAMPLE 251-[3-(Benzoylthio)-2-methyl-1-oxopropyl]-5-methoxy-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt

2,3-Dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid from Example 24 (2.61 g.) was added to a stirring mixture of4-dimethylaminopyridine (0.122 g.), thiobenzoic acid (95% purity, 1.6g.), and acetone (70 ml.) under a nitrogen atmosphere. The reactionmixture was heated at reflux for 8 hours and then chilled in a freezer.The precipitate was removed by filtration. The filtrate was evaporatedon a rotary evaporator under reduced pressure to give a resinousmaterial. The residue was dissolved in methylene chloride, and themethylene chloride solution was washed twice with 1N cold hydrochloricacid, then twice with saline, and dried over anhydrous sodium sulfate.Evaporation of the methylene chloride solution on a rotary evaporatorunder reduced pressure gave a resinous material which was dissolved inacetonitrile. Dicyclohexylamine was added dropwise to the chilledacetonitrile solution until the pH of the solution reached toapproximately 8. The resulting mixture was chilled in ice, and aprecipitate was collected on a filter, and washed with acetonitrile.Recrystallization of the filter residue from ethanol gave1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-5-methoxy-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine salt (0.9 g.) which melted at 204°-206°.

Analysis for: C₂₁ H₂₁ NO₅ S.C₁₂ H₂₃ N: Calculated: C, 68.24; H, 7.64; N,4.82. Found: C, 68.28; H, 7.62; N, 4.95.

EXAMPLE 261-[3-(Benzoylthio)-2-methyl-1-oxopropyl]-5-methoxy-2,3-dihydro-1Hindole-2-carboxylicacid

The title compound was prepared from the corresponding dicyclohexylaminesalt obtained in Example 25 (m.p. 204°-206°) by treatment with 5%aqueous potassium hydrogen sulfate solution as described in Example 15.

EXAMPLE 272,3-Dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-5-methoxy-1H-indole-2-carboxylicacid

The title compound was prepared from1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-5-methoxy-2,3-dihydro-1H-indole-2-carboxylicacid of Example 26 by treatment with methanolic ammonia as described inExample 5.

EXAMPLE 282,3-Dihydro-5-methoxy-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acidethyl ester

By substituting 2,3-dihydro-5-methoxy-1H-indole-2-carboxylic acid ethylester for 2,3-dihydro-1H-indole-2-carboxylic acid ethyl ester in theprocedure for Example 6,2,3-dihydro-5-methoxy-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acidethyl ester was prepared.

Analysis for: C₁₅ H₁₇ NO₄ : Calculated: C, 65.44; H, 6.22; N, 5.09.Found: C, 65.45; H, 6.14; N, 4.89.

EXAMPLE 292,3-Dihydro-5-methoxy-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acid

By substituting2,3-dihydro-5-methoxy-1-(1oxo-2-propenyl)-1H-indole-2-carboxylic acidethyl from Example 28 for2,3-dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester in the procedure for Example 24, the titled compoundwas obtained.

EXAMPLE 301-[3-(Benzoylthio)-1-oxo-propyl]-2,3-dihydro-5-methoxy-1H-indole-2-carboxylicacid

By substituting2,3-dihydro-5-methoxy-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acidfrom Example 29 for2,3-dihydro-1-(1-oxo-2-propenyl)-1H-indole-2-carboxylic acid in theprocedure of Example 8, the titled compound was prepared.

EXAMPLE 312,3-Dihydro-1-(3-mercapto-1-oxopropenyl)-5-methoxy-1H-indole-2-carboxylic

The titled compound was prepared from1-[3-(benzolythio)-1-oxopropyl]-2,3-dihydro-5-methoxy-1H-indole-2-carboxylicaicd from Example 30 by treatment with methanolic ammonia as describedin Example 4.

EXAMPLE 32 5-Chloro-2,3-dihydro-1H-indole-2-carboxylic acid ethyl ester

By substituting 5-chloroindole-2-carboxylic acid ethyl ester (B.Hearth-Brown and P. G. Philpott, J. Chem. Soc., 1965, 7185) for5-methoxyindole-2-carboxylic acid ethyl ester in the procedure ofExample 22, 5-chloro-2,3-dihydro-1H-indole-2-carboxylic acid ethylester(m.p. 51°-53°) was prepared.

Analysis for: C₁₁ H₁₂ ClNO₂ : Calculated: C, 58.54; H, 5.36; N, 6.21.Found: C, 58.57; H, 5.23; N, 6.31.

EXAMPLE 335-Chloro-2,3-dihydro-(2-methyl-1-oxo-2-propenyl)-1Hindole-2-carboxylicacid ethyl ester

By substituting 5-chloro-2,3-dihydro-1Hindole-2-carboxylic acid ethylester from Example 32 for 2,3-dihydroindole-2-carboxylic acid ethylester in the procedure of Example 1,5-chloro-2,3-dihydro-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester was obtained as an oil.

Analysis for: C₁₅ H₁₆ ClNO₃ : Calculated: C, 61.33; H, 5.49; N, 4.77.Found: C, 60.94; H, 5.60; N, 4.64.

EXAMPLE 345-Chloro-2,3-dihydro-1-(2-methyl-1-oxo-2propenyl)-1H-indole-2-carboxylicacid

By substituting5-chloro-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester from Example 33 for2,3-dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid ethyl ester in the procedure of Example 24,5-chloro-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid was prepared.

EXAMPLE 351-[3-(Benzoylthio)-2-methyl-1-oxopropyl]-5-chloro-2,3-dihydro-1H-indole-2-carboxylicacid

By substituting5-chloro-2,3-dihydro-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid from Example 34 for2,3-dihydro-5-methoxy-1-(2-methyl-1-oxo-2-propenyl)-1H-indole-2-carboxylicacid in the procedure of Example 25,1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-5-chloro-2,3-dihydro-1H-indole-2-carboxylicacid, dicyclohexylamine was obtained. The latter salt was then treatedwith 5% aqueous potassium hydrogen sulfate as in Example 15 to give thetitled compound.

EXAMPLE 365-Chloro-2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl-1H-indole-2-carboxylicacid

Treatment of1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-5-chloro-2,3-dihydro-1H-indole-2-carboxylicacid from Example 35 with methanolic ammonia as described in Example 4,gave the titled compound.

EXAMPLE 37 2,3-Dihydro-1H-indole-2-carboxylic acid

METHOD A

2,3-Dihydro-1H-indole-2-carboxylic acid ethyl ester (19.1 g.) was partlydissolved in methanol (200 ml.) at room temperature. An aqueouspotassium hydroxide solution obtained by dissolving 6.56 g. of KOHpellets (86% purity) in 70 ml. of water was added to the methanolicsolution. The resulting solution was stirred under nitrogen atmosphereat room temperature for 1.5 hours. The reaction mixture was concentratedon a rotary evaporator under reduced pressure to approximately 100 ml.,then transferred into an Erlenmyer flask. The chilled solution wasacidified first with chilled concentrated, then with dilute hydrochloricacid to pH ca. 5. Scratching of the resulting mixture while chillingcaused separation of a precipitate which was collected on a filter andwashed with cold water repeatedly to give 12.7 g. (76% yield) theproduct, m.p. 165°-170° dec.

Analysis for: C₉ H₉ NO₂.1/4H₂ O (167.67): Calculated: C, 64.47; H, 5.71;N, 8.35. Found: C, 64.64; H, 5.78; N, 8.25.

METHOD B

A mixture of 2,3-dihydro-1H-indole-2-carboxylic acid ethyl ester (9.56g.), 80% aqueous DMSO-(250 ml.) and potassium hydroxide (86% pellets,3.26 g.) was allowed to stir under nitrogen atmosphere at roomtemperature overnight, then evaporated on a rotary evaporator undervacuum to give a thick oily residue. The residue was dissolved in water(100 ml.). Several drops of 2N aq NaOH solution was added to thesolution to make it slightly alkaline. The aqueous solution was washedwith ether several times to remove any unreacted starting material, thenacidified while chilling in ice first with concentrated, then withdilute hydrochloric acid to pH ca. 5, whereby a precipitate separated.The mixture was chilled in ice, the precipitate was collected on afilter and washed with cold water. The product thus obtained melted at176°-179° dec. and weighed 8.73 g. (100%).

Analysis for: C₉ H₉ NO₂.1/6H₂ O (166.17): Calculated: C, 65.05; H, 5.66;N, 8.43. Found: C, 65.23; H, 5.67; N, 8.28.

EXAMPLE 38 R-3-Benzoylthio-2-methylpropanoyl Chloride

To a stirred mixture of thionyl chloride (30 ml., Aldrich Chemical Co.)and l-S-3-benzoylthio-2-methylpropanoic acid (13.44 g.) in a 100 ml.round bottom flask capped with a calcium chloride drying tube was addedtwo drops of triethylamine. The stirring was continued at roomtemperature for 7 hours, and the reaction mixture was evaporated on arotary evaporator under reduced pressure. The liquid residue thusobtained was kept under high vacuum for several hours.

EXAMPLE 39l-(S)-1-[(S)-3-(Benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid

(Method B)

To a stirred suspension of 2,3-dihydro-1H-indole-2-carboxylic acid (9.79g.) in methylene chloride (250 ml.) was added triethylamine (12.3 g.).The clear solution thus obtained was chilled in ice.R-3-Benzoylthio-2-methylpropanoyl chloride (the entire amount obtainedfrom 13.44 g. of the corresponding acid in Example 38) dissolved in 50ml. of methylene chloride was added slowly under vigorous stirring. Theice-bath was removed in 15 minutes, and the stirring was continued for2.5 hours. The reaction mixture was washed with 5% aqueous potassiumhydrogensulfate solution 3 times (250 ml., 200 ml. and 150 ml.), thenwith saline (twice), and dried over anhydrous sodium sulfate.Evaporation of the methylene chloride on a rotary evaporator underreduced pressure (in a large round bottom flask) gave a resinous residuewhich was kept under high vacuum for ca. 1 hour. The residue wasdissolved in acetonitrile (150 ml.), and the solution was chilled.Dicyclohexylamine (DCHA, 11 g., to pH 7.5-8.0 ) was added slowly withgood stirring to the cold solution, and the resulting mixture was keptin a refrigerator for 1.5 hours. The precipitate was collected on afilter, and the filter residue was washed with acetonitrile repeatedly.The DCHA salt method at 212.5°-215°, and weighed 16.1 g. (98% oftheory). Recrystallization from ethanol improved the m.p. to 219°-221°,giving 12.49 g. of the product, [α]_(D) ²⁴.5 =-68.93 (c=1.15%, EtOH).

Analysis for: C₂₀ H₁₉ NO₄ S.C₁₂ H₂₃ N: Calculated: C, 69.78; H, 7.69; N,5.09. Found: C, 69.38; H, 7.58; N, 5.26.

The salt (38.0 g.) was powdered in a mortar and pestle to fineparticles, and shaken vigorously with aqueous 5% KHSO₄ solution (450ml.) and ethyl acetate (200 ml.) in a separatory funnel. The ethylacetate layer was collected and the aqueous layer was extracted withethyl acetate two more times using 150 ml. and 100 ml. each time. Thecombined ethyl acetate extracts were washed with water, then withsaline, and dried over anhydrous sodium sulfate (or magnesium sulfate).The ethyl acetate was evaporated on a rotary evaporator under reducedpressure. In the later states of the evaporation the concentratedsolution was seeded with the product of Example 15, and the evaporationwas continued to dryness whereby a crystalline product was obtained as alarge mass. The mass was broken into small pieces and dissolved in ca.100 ml. of hot ethyl acetate. The filtered solution was diluted withhexane until it became cloudy, and was first chilled in ice then in afreezer. The precipitate was collected on a filter and washed withanhydrous ether giving 21.6 g. ofl-(S)-1-[(S)-3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid, m.p. 140.5°-142°, [α]_(D) ²⁵ =-184.9 (c=1.156%, EtOH). TLCobtained on a precoated Silica gel 60F-254 (available from Brinkmann) bydevloping with a solution of CH₂ Cl₂ (8)/EtOH(2)/Toluene(1)/NEt₃ (1)showed a spot at Rf 0.635 when detected under UV light. The diastereomerfrom the reaction showed its spot at Rf 0.54.

Analysis for: C₂₀ H₁₉ NO₄ S (369.42): Calculated: C, 65.02; H, 5.18; N,3.79. Found: C, 65.05; H, 5.04; N, 3.81.

EXAMPLE 40l-(S)-2,3-Dihydro-1-[(S)-3-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid

A mixture ofl-1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylicacid (5.0 g.) and 2-methoxyethylamine (40 ml.) in a 500 ml. round bottomflask was stirred under nitrogen atmosphere for 15 minutes at 0°, thenfor 10 minutes at room temperature. The excess amine was evaporated on arotary evaporator under reduced pressure to give an oil which was keptunder high vacuum for 15 minutes. The residue was dissolved in ca. 200ml. of cold oxygen-free water, and the aqueous solution was washed withfreshly opened anhydrous ether 3 times. Immediately (to avoid disulfideformation in alkaline conditions), the aqueous layer was acidified withdilute hydrochloric acid to pH ca. 1. The oily product thus separatedwas extracted with ether 3 times (150 ml., 100 ml., and 50 ml. in eachextraction). The combined ether extracts were washed with saline 3 timesand dried over anhydrous sodium sulfate for 1 hour. The ether wasevaporated on a rotary evaporator under reduced pressure, and theresidue was kept under high vacuum for 20 minutes. The solid productthus obtained was dissolved in ca. 30 ml. of hot ethyl acetate. Theethyl acetate solution was transferred quantitatively to filter paperusing a pipette and was carefully filtered using Reeve Angel filterpaper. The filtrate was diluted with hexane until it became cloudy(total volume of hexane used for the dilution was approximately 110 ml),and kept at room temperature for 1 hour, then chilled in ice for severalhours. The precipitate was collected on a filter and washed with amixture of ethyl acetate and hexane (3:10 by volume), giving 2.95 g.(82%) ofl-(S)-2,3-dihydro-1-[(S)-3-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid, which melted at 140.5-142°, [α]_(D) ²⁴ =-178.1 (c=1.135%, EtOH).TLC obtained as previously described showed a spot at Rf 0.45. There wasalso a very faint spot at Rf 0.25, which is believed to come from atrace amount of the disulfide impurity.

Analysis for: C₁₃ H₁₅ NO₃ S (265.3): Calculated: C, 58.84; H, 5.70; N,5.28. Found: C, 58.65; H, 5.73; N, 5.46.

EXAMPLE 41 d,l3,4,11,11a-Tetrahydro-4-methyl-1H,5H-[1,4]thiazepino[4,3-a]-indole-1,5-dione

d,l-2,3-Dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid (1.247 g.) from Example 4 was dissolved in dry methylene chloride(700 ml.), and the resulting solution was chilled in ice and stirredunder nitrogen atmosphere. To this solution was added4-dimethylaminopyridine (60 mg.), and the resulting mixture was stirredfor 5 minutes. Dicyclohexylcarbodiimide (1.02 g.) dissolved in ca. 10ml. of methylene chloride was added, and the stirred reaction mixturewas chilled in ice for 15 minutes, then allowed to warm room temperatureand stirred for 4 hours. The reaction mixture was concentrated on arotary evaporator under reduced pressure to approximately 100 ml. andchilled in dry ice-acetone. The precipitate that separated was collectedon a filter, and washed with methylene chloride. The combined filtrateand washings were evaporated on a rotary evaporator under reducedpressure to give an oily residue which solidified on standing. The solidmaterial was recrystallized from ether to give 3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]-thiazepino[ 4,3-a]indole-1,5-dione(0.7 g.), m.p. 108°-110°.

Analysis for: C₁₃ H₁₃ NO₂ S: Calculated: C, 63.13; H, 5.30; N, 5.66.Found: C, 63.29; H, 5.11; N, 5.73.

EXAMPLE 42d,l-3,4,11,11a-Tetrahydro-4-methyl-1H,5H-[1,4]thiazepino[4,3-a]-indole-1,5-dione

Treatment ofd,l-2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid from Example 5 which is diastereoisomeric with the startingmaterial used in Example 41 with dicyclohexylcarbodiimide according tothe procedure of Example 41 givesd,l-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]-thiazepino[4,3-a]indole-1,5-dionewhich is the diastereoisomer of the compound described in Example 41.

EXAMPLE 43(4S,11aS)-3,4,11,11a-Tetrahydro-4-methyl-1H,5H-[1,4]-thiazepino-[4,3-a]indole-1,5-dione

By substitutingl-(S)-2,3-dihydro-1-[(S)-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid for2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid in the procedure for Example 41, (4S,11aS)-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]thiazepino[4,3-a]indole-1,5-dionewas obtained.

EXAMPLE 44(4R,11aS)-3,4,11,11a-Tetrahydro-4-methyl-1H,5H-[1,4]thiazepino-[4,3-a]indole-1,5-dione

By substitutingd-(S)-2,3-dihydro-1-[(R)-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid for2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid in the procedure of Example 41, (4R,11aS)-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]thiazepino[4,3-a]indole-1,5-dionewas obtained.

EXAMPLE 45(4S,11aR)-3,4,11,11a-Tetrahydro-4-methyl-1H,5H-[1,4]thiazepino-[4,3-a]indole-1,5-dione

By substitutingl-(R)-2,3-dihydro-1-[(S)-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid for2,3-dihydro-1-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid in the procedure of Example 41,(4S,11aR)-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]thiazepino[4,3-a]indole-1,5-dionewas obtained.

EXAMPLE 46(4R,11R)-3,4,11,11a-Tetrahydro-4-methyl-1H,5H-[1,4]thiazepino-[4,3-a]indole-1,5-dione

By substitutingl-(R)-2,3-dihydro-1-[(R)-mercapto-2-methyl-1-oxopropyl]-1H-indole-2-carboxylicacid for 2,3-dihydro-1-mercapto-2-methyl-1-oxopropyl)-1H-2-carboxylicacid in the procedure of Example 41,(4R,11aR)-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]thiazepino[4,3-a]indole-1,5-dionewas obtained.

EXAMPLE 473,4,11,11a-Tetrahydro-1H,5H-[1,4]thiazepino[4,3-a]indole-1,5-dione

By substituting2,3-dihydro-1-(3-mercapto-1-oxopropyl)-1H-indole-2-carboxylic acid for2,3-dihydro-(3-mercapto-2-methyl-1-oxopropyl)-1H-indole-2-carboxylicacid in the procedure of Example 41,3,4,11,11a-tetrahydro-1H,5H-[1,4]thiazepino[4,3-a]-indole-1,5-dione wasprepared.

EXAMPLE 48

Similarly the following compounds are prepared.

9-Methoxy-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]thiazepino-[4,3-a]indole-1,5-dione

9-Chloro-3,4,11,11a-tetrahydro-4-methyl-1H,5H-[1,4]thiazepino-[4,3-a]indole-1,5-dione.

EXAMPLE 49 l-3-Benzoylthio-2-methyl propanoic acid

A solution of d-dehydroabietylamine [prepared from d-dehydroabietylamineacetate (127 g; 0.368 moles), triethylamine (39.2 g, 54 ml, 0.387moles), water (75 ml) and ethyl acetate (1500 ml) at 50°-55°] was cooledto 45° C. and added as rapidly as possible at 30° C. to a solution ofd,l-3-benzoylthio-2-methylpropionic acid (150 g, 0.66 moles) in ethylacetate (1500 ml). The temperature rose to 40° C., the solution wasseeded, cooled to 30° C. over 30 minutes, then to 20° C. over 30minutes. The solid was filtered, slurried with ethyl acetate (500 ml),refiltered, and washed with ethyl acetate (75 ml). The wet cake wasdissolved in ethanol 3A anhydrous (3000 ml) at 70°-75° C. for fiveminutes, filtering off any insolubles, cooled to 20° C. and allowed tostand one hour. The precipitate solid was filtered and dried in a vacuumoven at 35° C. to constant weight to provide the purel-3-benzoylthio-2-methyl propanoic acid, d-dehydroabietylamine salt(93.0 g), m.p. 153°-153.5°, [α]_(D) ²⁵ =+16.2° (C=2, THF), 54,5% yield.

The l-3-benzoylthio-2-methyl propanoic acid, d-dehydroabietylamine salt(100 g, 0.196 moles) was partitioned between methylene chloride (400 ml)and 1N-aqueous sodium hydroxide (200 ml., 0.2 mole) and the liquidsfiltered to break the emulsion formed. The methylene chloride layer wasseparated and washed with water (100 ml.). The aqueous layers werecombined and washed with methylene chloride (100 ml.). The aqueous layerwas brought to pH 3 with 1N-aqueous hydrochloric acid, and theprecipitated oil extracted with methylene chloride (150 ml. and 50 ml.).The dry methylene chloride extract was diluted with hexane (400 ml.) andthe solution was concentrated with stirring to 400 ml. not exceeding35°-40° C. The mixture was cooled with stirring at 20°-25° C. for onehour.

Filtration, washing with hexane (2×25 ml.) and drying in a vacuum oven(below 35° C.) provided l-3-benzoylthio-2-methylpropanoic acid (36.6 g.)(83.2% yield), m.p. 68.5°-69.5° C., [α]_(D) ²⁵ =-42.4° (C=2 in EtOH).

EXAMPLE 50 (S)-Phthaloylalanyl Chloride

A mixture of (S)-phthaloylalanine (32.88 g.), thionyl chloride (75 ml.),and triethylamine (4 drops) were stirred at room temperature overnight,then evaporated on a rotary evaporator under reduced pressure. Theresidue was dissolved in anhydrous ether, and the ether solution wasevaporated on a rotary evaporator under reduced pressure to give an oilyresidue. The dissolution of the residue in anhydrous ether followed byevaporation was repeated two additional times. The oily residuesolidified slowly at room temperature. The crystalline solid was placedin a high vacuum for several hours. The product melted at 51°-53°;[α]_(D) ²⁷ =-8.34 (c=1.04% CHCl₃).

EXAMPLE 51(S)-2,3-Dihydro-1-[(S)-2-(1,3-Dihydro-1,3-Dioxo-2H-Isoindol-2-yl)-1-Oxopropyl]-1H-Indole-2-CarboxylicAcid, Dicyclohexylamine

(S)-Phthaloylalanyl chloride (the entire amount from the previousexample, 0.15 mole) dissolved in a small amount of dry methylenechloride (60 ml.) was added over 10 min. to a chilled (0° C.) rapidlystirred solution of 2,3-dihydroindole-2-carboxylic acid (24.5 g., 0.15mole), triethylamine (30.7 g., 0.3 mole), and methylene chloride (700ml.) under nitrogen atmosphere. The resulting mixture was stirred at 0°C. for an additional 15 min., then at room temperature for 2 hr. Thereaction mixture was washed with 5% aqueous potassium bisulfate solution3 times (600 ml., 500 ml., and 400 ml.), then with saline twice, anddried over sodium sulfate. Evaporation of methylene chloride on a rotaryevaporator under reduced pressure gave an amorphous solid which wasdried in a high vacuum for several hours, giving a crude product (59 g.)as a diastereoisomeric mixture in the ratio of 6:4.

The product was dissolved in acetonitrile (300 ml.), then cooled toabout 10° C. Dicyclohexylamine (27 g.) was added slowly to theacetonitrile solution with vigorous stirring. The resulting mixture wasallowed to stand at room temperature for 1.5 hr., then in a refrigeratorfor 0.5 hr. The precipitate that separated was collected on a filter,and washed with acetonitrile (6 or 7 times with a total of 200 ml.),giving 28.0 g. of partially resolved product, m.p. 199°-201.5° C.[α]_(D) ²⁸ =-143.3° (c=1.12%, EtOH).

The product was dissolved in approximately 150 ml. of hot ethanol. Thesolution was allowed to cool to room temperature and then chilled in arefrigerator for 1-2 hours. The precipitate was collected on a filterand washed with chilled ethanol several times, then with acetonitrileseveral times. The product thus obtained melted at 201°-203° C., andweighed 21.25 g., [α]_(D) ²⁸ =-150.1° (c=1.01%, EtOH). Analytical samplemelted at 204.5°-206.5° C.; [α]_(D) ²⁵ =-156.45° (c=0.6% EtOH).

Analysis for: C₂₀ H₁₆ N₂ O₅.C₁₂ H₂₃ N: Calculated: C, 70.43; H, 7.20; N,7.70. Found: C, 70.26; H, 7.05; N, 7.70.

EXAMPLE 52(R)-2,3-Dihydro-1-[(S)-2-(1,3-Dihydro-1,3-Dioxo-2H-Isoindol-2-yl)-1-Oxopropyl]-1H-Indole-2-CarboxylicAcid, Dicyclohexylamine

Combined acetonitrile filtrate and washings from the previous example(Example 51) were filtered to remove a small amount of a precipitate,and evaporated on a rotary evaporator to dryness to give 27 g. ofamorphous solid, [α]_(D) ²⁵ =-8.01° (c=1.15%, EtOH).

Analysis for: C₂₀ H₁₆ N₂ O₅.C₁₂ H₂₃ N: Calculated: C, 70.43; H, 7.20; N,7.70. Found: C, 70.30; H, 7.29; N, 7.62.

EXAMPLE 53(S)-2,3-Dihydro-1-[(S)-2-(1,3-Dihydro-1,3-Dioxo-2H-Isoindol-2-yl)-1-Oxopropyl]-1H-Indole-2-CarboxylicAcid, Hemiethyl Acetate

Dicyclohexylamine salt (25.9 g.) of the title compound was shaken with5% aqueous potassium bisulfate solution (400 ml.), and the free acid wasextracted three times with ethyl acetate (total volume 550 ml.).

The combined extracts were washed with saturated aqueous sodium chloridesolution twice, and dried over anhydrous sodium sulfate. Evaporation ofthe ethyl acetate on a rotary evaporator under reduced pressure, then invacuo gave an amorphous solid (20 g.), [α]_(D) ²⁵ =-250.01° (c=1.165%,EtOH), ms (C.I.); m/e 265.

Analysis for: C₂₀ H₁₆ N₂ O₅.1/2 EtOAc:

Calculated: C, 64.70; H, 4.94; N, 6.86. Found: C, 64.58; H, 4.84; N,7.01.

EXAMPLE 54(S)-1-[(S)-2-Amino-1-Oxopropyl]-2,3-Dihydro-1H-Indole-2-Carboxylic Acid

(S)-2,3-Dihydro-1-[(S)-2-(1,3-dihydro-1,3-dioxo-2H-isoindo]-2-yl)-1-oxopropyl]-1H-indole-2-carboxylicacid, dicyclohexylamine (20.4 g.) was treated with 5% aqueous potassiumbisulfate solution (300 ml.), and the free acid that formed wasextracted three times with methylene chloride (combined extracts 450ml.). The combined extracts were washed with saline twice, then driedover anhydrous sodium sulfate. Evaporation of the methylene chloride ona rotary evaporator under reduced pressure, then in high vacuum gave anamorphous solid which was dissolved in methanol (200 ml.). Hydrazine(95%, 1.43 g.) was added to the methanol solution. The resulting mixturewas stirred under nitrogen atmosphere at room temperature for 24 hr.,then chilled in an ice-salt mixture for 3 hr. A precipitate(phthalhydrazide, 4.06 g.) was collected on a filter, and washed withmethanol. The combined filtrate and washings were evaporated on a rotaryevaporator under reduced pressure, then in vacuo to give a solidresidue. The residue was triturated with methylene chloride (ca. 250ml.) and filtered. The filter residue was washed with methylene chlorideseveral times and dried in vacuo. The crude product was dissolved inwater (ca. 50 ml.) at room temperature, and filtered. The filter residuewas washed with water. The combined filtrate and washings wereevaporated carefully on a rotary evaporator under reduced pressure togive a solid residue which was dried over phosphorous pentoxide in vacuoto give the title product (6.31 g.), [α]_(D) ²⁵ =-140.85 (c=1.44%,water). The analytical sample which was obtained by recrystallizationsfrom methanol melted at 171°-172° (when the melting point was determinedwith rapid heating, the compound melted at 206.5°-209°), [α]_(D) ²⁵=-161.17° (c=1.065%, EtOH).

Analysis for: C₁₂ H₁₄ N₂ O₃ : Calculated: C, 61.52, H, 6.02; N, 11.96.Found: C, 61.44; H, 6.20; N, 12.26.

EXAMPLE 55(-)-(S)-1-[(2S)-2-[[(1S)-1-(Ethoxycarbonyl)-3-Phenylopropyl]Amino]-1-Oxopropyl]-2,3-Dihydro-1H-Indole-2-CarboxylicAcid, Maleate

A mixture of(S)-1-[(S)-2-amino-1-oxopropyl]-2,3-dihydro-1H-indole-2-carboxylic acid(2.34 g.), triethylamine (1.01 g.), 2-oxo-4-phenylbutanoic acid ethylester (2.6 g.), powdered molecular sieve 3A (10 g.), anhydrous ethanol(250 ml.) and Raney nickel (3.0 g.) was hydrogenated at room temperatureusing a Paar hydrogenator with 45 psi hydrogen pressure until uptake ofhydrogen ceased. The reaction mixture was filtered through a bed ofCelite, and the filter residue was washed with ethanol repeatedly. Thecombined filtrate and washings were evaporated on a rotary evaporatorunder reduced pressure to give a resinous residue. The residue wasdissolved in a mixture of water (80 ml.) and ether (25 ml.), and themixture was made alkaline to pH 9.6 by addition of dilute aqueous sodiumhydroxide solution. The ether layer was separated and the aqueous layerwas washed with ether two additional times. The aqueous solution wasacidified to pH 4.2 by addition of dilute hydrochloric acid, thensaturated with sodium chloride. The acidic aqueous solution wasextracted with ethyl acetate 4 times. The combined extracts were driedover anhydrous sodium sulfate and evaporated on a rotary evaporator todryness. The residue was dissolved in a small amount of ethyl acetate(ca. 5 ml.). Maleic acid (0.9 g.) was added to the solution and theresulting mixture was stirred at room temperature until a clear solutionwas obtained (ca. 1.5 hr.). Anhydrous ether (ca. 70 ml.) was addedslowly with vigorous stirring until no additional milky precipitateseparated. The mixture was chilled and the supernatant liquid wasdecanted. The residue was redissolved in a small amount of ethylacetate. The solution was added dropwise to a large amount of anhydrousether (ca. 3.5 l.), whereby most of the product was dissolved. The ethersolution was filtered and the filtrate was evaporated on a rotaryevaporator to ca. 150 ml., and chilled in ice for several hours. Thesupernatant liquid was decanted and the residue was dissolved inanhydrous ether (ca. 2 l.) with warming on a steam bath. The solutionwas concentrated on a rotary evaporator to ca. 100 ml. and chilled inice. The supernatant liquid was decanted and collected separately (seefollowing example). This recrystallization was repeated 8 more times togive the title product (210 mg.) as fine white powder. The compound didnot have a definite melting point (melted at 69°-80°), and showed onespot on TLC (silica gel, CH₂ Cl₂ (4)/MeOH (1)) with Rf 0.41, [α]_(D) ²⁵=-84.6° (c=0.755%, MeOH).

Analysis for: C₂₄ H₂₈ N₂ O₅.C₄ H₄ O₄ : Calculated: C, 62.21; H, 5.97; N,5.18. Found: C, 62.27; H, 5.97; N, 5.38.

EXAMPLE 56(-)-(S)-1-[(2S)-2-[[(1R)-1-(Ethoxycarbonyl)-3-Phenylpropyl]Amino]-1-Oxopropyl]-2,3-Dihydro-1H-Indole-2-CarboxylicAcid, Maleate

The ether decants from the previous example were combined andconcentrated on a rotary evaporator to ca. 100 ml., and chilled in ice.The supernatant liquid was decanted and the residue was purified in thesame fashion as described in the previous example to give the titleproduct (360 mg.) as a very light white powder. The compound did nothave a definite melting point and showed a spot on TLC (silica gel, CH₂Cl₂ (4)/MeOH(1)) at Rf 0.48, [α]_(D) ²⁷ =-101.18° (c=0.99%, MeOH).

Analysis for: C₂₄ H₂₉ N₂ O₅.C₄ H₄ O₄ : Calculated: C, 62.21; H, 5.97; N,5.18. Found: C, 62.87; H, 6.09; N, 5.48.

EXAMPLE 57

In the in vitro assay for angiotensin converting enzyme inhibitionutilizing the rabbit lung extract according to the procedure of Cushmanet al., Biochem, Pharmacol., 20, 1637-1648 (1971), the following resultswere obtained:

    ______________________________________                                        Compound of                                                                   Example             IC.sub.50                                                 ______________________________________                                        54                  3.1 × 10.sup.-6 M                                   55                  1.18 × 10.sup.-7 M                                  56                  9 × 10.sup.-7 M                                     ______________________________________                                    

EXAMPLE 58

When tested in the normotensive conscious rat according to the procedureof Rubin et al., J. Pharmacol. Exp. Ther., 204, 271-280 (1978), thecompound of Example 55 inhibited the vasopressor action of Angiotensin I46 percent 2 hours after being administered orally at a dose of 1 mg/kg.of body weight.

EXAMPLE 59

When administered orally in the spontaneously hypertensive rat, thecompound of Example 55 showed the following reductions in bloodpressure:

    ______________________________________                                                     Reduction of                                                     Dose         Systolic BP                                                                              No. of                                                mg/kg.       mm. Hg.    Subjects                                              ______________________________________                                        2.5          -13        4                                                     5.0          -23        4                                                     10.0         -33        4                                                     ______________________________________                                    

What is claimed is:
 1. A compound of the formula: ##STR17## wherein: R₁is hydrogen, lower alkyl, aryl, or aralkyl;R₁₅ is hydrogen or loweralkyl; X is hydrogen, hydroxy, lower alkyl, lower alkoxy or halogen; Yis hydrogen, lower alkyl or aryl; and Z is a carboxylic acid protectinggroup; wherein aryl refers to phenyl or phenyl substituted by a halogen,a lower alkyl, or a lower alkoxy group; and aralykyl refers to benzyl orbenzyl substituted on the phenyl ring by a halogen, a lower alkyl or alower alkoxy group.
 2. A compound of the formula: ##STR18## wherein: R₁is hydrogen, lower alkyl, aryl or aralkyl;R₁₅ is hydrogen or loweralkyl; R₅ is hydroxy, amino, or lower alkoxy; X is hydrogen, hydroxy,lower alkyl, lower alkoxy or halogen; and Y is hydrogen, lower alkyl oraryl; wherein aryl refers to phenyl or phenyl substituted by a halogen,a lower alkyl, or a lower alkoxy group; and aralkyl refers to benzyl orbenzyl substituted on the phenyl ring by a halogen, a lower alkyl or alower alkoxy group.